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Biomedical subjects

M Komiyama

Publications and source records attributed to M Komiyama.

At least 19 recordsLinked to original sources
PubMed2002

Simultaneous dissection of intra- and extracranial vertebral artery. Report of two cases and review of literature.

Two patients who developed subarachnoid haemorrhage are presented. The first patient was a 41-year-old woman whose angiograms showed right extracranial vertebral artery (VA) dissection starting at the C2 level extending to the intracranial VA near the VA union. Proximal occlusion of the right VA by the endovascular approach was performed. The second patient was a 57-year-old man whose angiograms showed the left intracranial VA dissection distal to the posterior inferior cerebellar artery and an extracranial aneurysmal dilatation of the left VA at the C1 level and extracranial VA dissection in the V3 portion of the right VA. Left intracranial VA dissection was surgically trapped, and the remaining lesions were conservatively treated. Simultaneous dissection of the intracranial and extracranial portions of the VA is rare. Such lesions usually cause brain ischaemia, but may cause intracranial subarachnoid haemorrhage.

Adult↗
PubMed2002

Transfemoral, transvenous embolisation of dural arteriovenous fistula involving the isolated transverse-sigmoid sinus from the contralateral side.

BACKGROUND: A dural arteriovenous fistula (AVF) involving the transverse-sigmoid (T-S) sinus which is occluded at its proximal and distal ends i.e., an isolated sinus, runs the risk of haemorrhaging or causing serious neurological deficits as a result of its retrograde leptomeningeal venous drainage. While lesions of this type have not been considered to be treatable by percutaneous, transvenous embolisation, this paper challenges this view. CASE PRESENTATION: Two middle-aged men with dural AVFs involving the isolated left T-S sinus presented with motor aphasia due to focal brain edema or haemorrhage. Under local anaesthesia, transfemoral, transvenous embolisation was performed with a microcatheter that was passed through the occluded proximal transverse sinus from the right (contralateral) side. The isolated sinus was then occluded with platinum coils. This embolisation resulted in angiographic and clinical cure of dural AVFs in both patients. INTERPRETATION: Transfemoral, transvenous embolisation is a therapeutic alternative for the treatment of dural AVFs involving the isolated T-S sinus. Embolisation obviates the need for craniotomy and general anaesthesia, which are required for the established modes of treatment, i.e., direct surgery or direct percutaneous sinus packing.

Angiography, Digital Subtraction↗
PubMed2001

Photocontrol of DNA duplex formation by using azobenzene-bearing oligonucleotides.

The duplex-forming activities of oligonucleotides can be photomodulated by incorporation of an azobenzene unit. Upon isomerizing the trans-azobenzene to the cis form by irradiation with UV light, the T(m) value of the duplex (with the complementary DNA) is lowered so that the duplex is dissociated. The duplex is formed again when the cis-azobenzene is converted to the trans-azobenzene by irradiation with visible light. The photoregulation is successful irrespective of the position of the azobenzene unit in the oligonucleotides. The trans-azobenzene in the oligonucleotides intercalates between two DNA base pairs in the duplexes and stabilizes them because of a favorable enthalpy change. The nonplanar structure of a cis-azobenzene is unfavorable for such an interaction. These photoresponsive oligonucleotides are promising candidates for the regulation of various bioreactions.

Azo Compounds↗
PubMed2001

Leptomeningeal contrast enhancement in moyamoya: its potential role in postoperative assessment of circulation through the bypass.

Leptomeningeal contrast enhancement (LMCE) is one of the MRI features of moyamoya. Its clinical significance, however, is not elucidated. Our purpose was to characterise LMCE on MRI and to evaluate its role in the assessment of circulation through a surgically established bypass in moyamoya. We studied 16 patients with idiopathic moyamoya (seven males, nine females, includingt four children, aged 7 to 54 years, mean 24 years) who underwent T1-weighted MRI before and after intravenous contrast medium. The presence of LMCE, its intensity and anatomical distribution, catheter angiographic findings, and relation of LMCE to the bypass surgery were assessed. More LMCE was seen in the cerebrum in most patients with moyamoya than in normal controls. LMCE in the brain stem and cerebellum was minimal, similar to that seen in the controls. LMCE was less prominent following surgery than before operation or in patients who did not undergo surgery. In three patients examined both before and after operation LMCE became less prominent following bypass surgery. As LMCE becomes less prominent after "effective" bypass surgery, this may be used for evaluation of effectiveness of surgery in moyamoya.

Adult↗
PubMed2001

Distal stump of an occluded intracranial vertebral artery at the vertebrobasilar junction mimicking a basilar artery aneurysm.

The distal stump of an occluded intracranial vertebral artery (VA) can mimic a basilar artery aneurysm of the vertebrobasilar junction. Their differentiation is crucial to establishing the appropriate treatment. We report two cases with occlusion of the distal stump of the VA due to atherosclerosis and arterial dissection. Magnetic resonance images with three-dimensional constructive interference in steady state sequences are useful in revealing the occluded segment as a continuous anatomical structure from the proximal VA to the basilar artery. This information may prevent unnecessary exploratory surgery for a suspected basilar artery aneurysm.

Adult↗
PubMed2001

Site-selective artificial ribonuclease using pinpoint RNA activation.

An acridine residue attached to the end or the inside of a DNA activates the target phosphodiester linkages in complementary RNA. Due to this pinpoint activation, the RNA is site-selectively and efficiently cleaved at these linkages by various free metal ions under mild condition. Spectroscopic analyses show that the acridine moiety is sandwiched between neighboring bases, and pushes the opposite nucleotide out of the hetero-duplex.

Acridines↗
PubMed2001

Regulation of aggregated structure of dye molecules by DNA hybridization.

Dye H-aggregates were successfully created by introducing multiple Methyl Red molecules consecutively in the single stranded DNA. By the presence of its complementary DNA, however, the H-band disappeared and new peak appeared at longer wavelength, indicating that aggregated structure changed by the duplex formation. Thus, supramolecular structure of the dye aggregates was successfully controlled by use of DNA.

Azo Compounds↗
PubMed2001

Photo-regulation of RNA polymerase reaction by use of modified DNA carrying an azobenzene.

Transcription reaction by T7-RNA polymerase was photo-regulated on the basis of two strategies as depicted in Scheme 1. It was found that incorporation reaction of azobenzene-tethered uridine triphosphate proceeded only when azobenzene took trans-form (Scheme 1(A)). On the other hand, the transcription was more efficient when the azobenzene moiety, tethered to the non-template strand of the promoter DNA, was in its cis-form under UV irradiation (Scheme 1(B)). Thus, azobenzene-tethered DNAs are promising for the photo-regulation of gene-expression.

Azo Compounds↗
PubMed2001

Trinuclear Cu(II) complex for internucleoside linkage-specific cleavage of RNA.

Trinuclear Cu(II) complex of N,N,N',N',N",N"-hexa[(2-pyridyl)methyl]-1,3,5-tris(aminomethyl)benzene (L3A) exhibits remarkable substrate-specificity for hydrolysis of 2'-->5' and 3'-->5' ribonucleotides. Up(2'-->5')U is hydrolyzed much efficiently than is Up(3'-->5')U, but Ap(3'-->5')A is overwhelmingly preferable to Ap(2'-->5')A.

Copper↗
PubMed2001

Rapid normalization of marked dilatation of the cerebral duro-venous system in a newborn infant mimicking a great vein of Galen varix.

A newborn infant with a marked dilatation of the cerebral duro-venous system is presented. The patient was diagnosed as having a vein of Galen aneurysmal varix by a cranial ultrasound examination immediately following delivery. Computed tomographic angiography on the following day, however, showed a marked dilatation of the cerebral duro-venous system, including the great vein of Galen, superior sagittal sinus, torcular herophili and transverse sinuses. There were no arteriovenous fistulas at the vein of Galen. Dilatation of the duro-venous system and concomitant heart failure subsided rapidly after intravenous administration of indomethacin for the treatment of the patent ductus arteriosus on the fourth day of life. Dilatation of the duro-venous system in a newborn infant should be differentiated from any form of vein of Galen aneurysm.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2001

The second EF-hand is responsible for the isoform-specific sorting of myosin essential light chain.

It has been known that isoforms of myosin essential light chain (LC) exhibit the isoform-specific sorting within cardiac myocytes and fibroblasts. In order to analyze which domain of LC is responsible for the sorting, various chimeric cDNA constructs between human nonmuscle isoform (LC3nm) and chicken fast skeletal muscle isoform (LC3f) were generated and expressed in cultured chicken cardiac myocytes. If chimeras contained LC3f sequence at the place that was restricted by BssHII and PstI, they were preferentially sorted to sarcomeres and precisely localized at A-bands, and their incorporation levels into the A-bands were identical with that of the wild type LC3f. However, other chimeras were distributed throughout the cytoplasm like the wild type LC3nm. Comparison of amino acid sequences revealed that 12 amino acids are different between chicken LC3f and human LC3nm in the BssHII-PstI fragment, and these amino acids are located within the second EF-hand of LC. These results indicated that the second EF-hand is responsible for the isoform-specific sorting of LC. Although the second EF-hand is not included in the key contacts with myosin heavy chain, it is supposed that this domain is important for the relative disposition of neighboring domains. Thus, the 12 amino acids in the second EF-hand might play a key role for modulation of overall configuration of LC, thereby influencing the precise association of the key contacts.

Amino Acid Sequence↗
PubMed2001

Neonatal exposure to genistein reduces expression of estrogen receptor alpha and androgen receptor in testes of adult mice.

We investigated the long-term estrogenic influence of genistein on the male reproductive system in mice. Newborn ICR male mice were treated with genistein (10, 100, or 1,000 microg/mouse) for neonatal 5 days. As positive control, administration of diethylstilbestrol (0.5-50 microg/mouse) was carried out. In mice exposed to genistein,we examined weight of testes, sperm counts, sperm motility, and mRNA expression levels of estrogen receptor a (ERalpha) and androgen receptor (AR) at 4, 8 or 12 weeks after birth. Moreover, at 12 weeks of age, we evaluated protein level of ERalpha. In our conventional reproductive-toxicological study (weight of testes, sperm counts and sperm motility), neonatal transient exposure to genistein did not show adverse effects on the male reproductive system in 4, 8 or 12 week old mice. However, in mice treated with genistein mRNA expression levels of ERa and AR were reduced at 8 weeks. This reduction was recovered at 12 weeks in mice treated with a lower dose (10 microg) of genistein but not in those with higher doses (100 microg and 1,000 microg). In addition, ERa protein levels tended to decrease in 12 weeks of adulthood. Our results exhibited that the disruption of gene expression continued for long term such as 3 months after administration of genistein, even if no effect was found at conventional reproductive-toxicological level. We have shown that neonatal administration of weak estrogenic compound (genistein) affects male reproductive organs at molecular levels in adulthood.

Animals↗
PubMed2001

"Early" apoplexy due to traumatic intracranial aneurysm--case report.

A 76-year-old man presented with a traumatic aneurysm of the left internal carotid artery which caused repeated subarachnoid hemorrhages within 20 hours of a fall from a height. Early computed tomography (CT) detected no brain abnormalities, but repeat CT found subarachnoid hemorrhage. Internal carotid angiography detected a pseudoaneurysm, which was not treated because of his poor clinical condition. He died of multiple organ failure. Early detection of a traumatic intracranial aneurysm is important for the prevention of aneurysmal rupture, or "delayed" apoplexy. Review of 171 cases with traumatic aneurysms from the literature found that false negative angiography occurred only in three cases on post-trauma day 7 and thereafter. Early diagnostic angiography within a week of the initial trauma is indicated if traumatic aneurysm is suspected to detect early signs of irregularity, spasm, and narrowing of the arterial wall. Repeat angiography is indicated if aneurysmal formation is still highly suspected in spite of negative initial angiography.

Acute Disease↗
PubMed2001

Moyamoya disease and coronary artery disease--case report.

A 26-year-old female with idiopathic moyamoya disease developed chest pain with concomitant ST depression on electrocardiography. Coronary angiography detected no stenotic lesions in the epicardial coronary arteries. The clinical diagnosis was vasospastic angina pectoris. She was medicated with calcium antagonists, which reduced the frequency of chest pain episodes. Angina pectoris is a rare occurrence in young patients with moyamoya disease. Coronary artery disease and moyamoya disease may have common etiological factors.

Adult↗